Steel with high hardness and excellent toughness
a technology of excellent toughness and hardness, applied in the field of steel with high hardness and excellent toughness, can solve the problems of degrading toughness, intergranular fracture, and steel material may break on impact, and achieve the effect of suppressing intergranular fractures that would degrade toughness, low risk, and superior hardness and toughness
Active Publication Date: 2020-05-28
OSAKA UNIV +1
View PDF0 Cites 3 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
The present invention relates to a hypereutectoid steel with a unique structure comprising a dual phase of martensitic structure and spheroidized carbide. The steel has a low risk of cracking due to the uniform distribution of cementite particles in a nearly spherical shape. Additionally, the steel has high hardness and toughness with low intergranular fracture. This steel material can be used to produce components for automobiles and industrial machines requiring high hardness and toughness.
Problems solved by technology
Increasing the hardness of a steel material, however, degrades its toughness, so the steel material may break on impact.
In the case where a steel includes alloy constituents such as Mn, Ni, and Cr in its components, carbides of Mn, Ni, and Cr would precipitate at the prior austenite grain boundaries during the process of tempering after quenching, thereby causing intergranular fracture.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
examples
[0056]Steels having the chemical compositions of Inventive Examples Nos. 1 to 7 and Comparative Examples Nos. 8 to 11 shown in Table 1 below were produced in a 100-kg vacuum melting furnace. The obtained steels were each subjected to hot forging at 1150° C. to obtain a round bar having a diameter of 26 mm, which was then cut into 250 mm in length to form a test sample. Next, heat treatment was carried out, as pearlitization processing as shown in FIG. 2, in which each round bar steel was held at 1000° C. for 15 minutes and then gas-cooled to 600° C. It was held at 600° C. for three hours and then air-cooled. Thereafter, spheroidizing annealing was carried out, as shown in FIG. 3, in which heat treatment of furnace-cooling the bar steel from 780° C. to 650° C. was repeated twice. The resultant bar steels were then each shaped roughly into a 10-RC notched Charpy impact test specimen, which was then subjected to processing as shown in FIG. 4. Specifically, each test specimen was held a...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
| Property | Measurement | Unit |
|---|---|---|
| aspect ratio | aaaaa | aaaaa |
| particle size | aaaaa | aaaaa |
| grain size | aaaaa | aaaaa |
Login to View More
Abstract
A steel with high hardness and excellent toughness contains, in mass %, 0.55-1.10% C, 0.10-2.00% Si, 0.10-2.00% Mn, 0.030% or less P, 0.030% or less S, 1.10-2.50% Cr, and 0.010-0.10% Al, with the balance consisting of Fe and unavoidable impurities. The structure of the steel after quenching is a dual phase structure of martensitic structure and spheroidized carbide. Spheroidized cementite particles with an aspect ratio of 1.5 or less constitute at least 90% of all cementite particles. The proportion of the number of spheroidized cementite particles on the prior austenite grain boundaries to a total number of cementite particles is 20% or less.
Description
TECHNICAL FIELD[0001]The present invention relates to steels with high hardness and excellent toughness, among steels for mechanical structure use which are used for components of automobiles or various industrial machines.BACKGROUND ART[0002]Steels used for components of automobiles or various industrial machines, especially steels used for components requiring wear resistance and excellent fatigue characteristics, are generally quenched to increase the hardness before being used. A steel material primarily having a martensitic structure as a result of quenching has its hardness determined by its C content; an increased C content leads to an increased hardness of the steel material. Increasing the hardness of a steel material, however, degrades its toughness, so the steel material may break on impact. The steel material thus requires a good balance between hardness and toughness.[0003]As conventional techniques for addressing such requirements, a steel having both excellent wear re...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(United States)
IPC IPC(8): C22C38/58C22C38/34C22C38/06C22C38/44C22C38/46
CPCC22C38/46C21D6/008C22C38/06C22C38/34C21D6/004C21D6/005C21D2211/008C21D2211/001C22C38/58C22C38/44C21D2211/003C21D6/00C22C38/38C21D6/02C21D2211/004C22C38/18C21D1/613
Inventor MINAMINO, YORITOSHITAKAYAMA, TAKEMORIYAMAMOTO, KOJIHIRATSUKA, YUSUKE
Owner OSAKA UNIV